Apparatus for treating steel



APHl 16, 1929, l H. w. TINKER 1,709,160

APPARATUS FOR TREATING STEEL April 16, 1929.

H. W. TINKER APPARATUS FOR TREATING STEEL Filed NOV- 13, 1926 3Sheets-Sheet Hamam @Ko/6% M2M, E f/z? j,

Patented Apr. 16, 1929.

UNITED STATES PATEN T oFF-ICE.

HERBERT W. TINKER, 0F MILWAUKEE, WISCONSIN, ASSIGNOR TO FEDERAL PRESSED.STEEL COMPANY, 0F MILWAUKEE, WISCONSIN, A CORPORATION 0F WISCONSIN.

APPARATUS FOR TREATING STEEL.

v Application led November 13, 1926. Serial No. 148,128.

My invention relates generally to apparatus for treating steel, and hasto do particularly with air treatment of spring steel such, for example,as may be used for automobile bumpers and springs, and wherein4thetinished product is given the desired temper to produce the desiredhardness and toughness to withstand ordinary impacts to which the samemay be subjected without breakage or permanent distort-ion.

In the course of manufacture of many steel products, various heat-treatments are elnployed to give the steel the proper metallurgicalproperties to condition the same f or the particular use intended. Incertam 1nl stances, for example, the manufacture of automobilc bumpersand springs, it has been necessary to subject the steel which forms thesame or certain of the parts of the same to a heat treatment fortempering the same so as to provide suflicient toughness and hardness inthe finished steel parts, without brittleness, at the same timeproviding the desired tensile strength, elasticity and physicalcharacteristics to render the same capable of receiving impact and loadwithout breakage or permanent distortion.

The usual method employed in such 1nstances for tempering the steel tothe desired extent, is the well-known oil heat treatmg method. Generallyspeaking, in carrying out this customary oil heat treating method, asfor example in the manufacture of automobile bumpers, or springs, themetal is first heated' to the desired high heat suicient to permit thesame to be readily formed to the shape intended. This heating operationis then followed by the shaping of the bar by suitabletools. After thebar has thus been shaped, it is dipped in a cool oil bath where it ischilled and quickly cooled. In some eases the shaped bar may be heatedto a desired high heat after the shaping operation and then, while at adesired high heat, dipped in the cool oil bath and rapidly cooled andchilled as stated. In either case. the rapid cooling makes the metalvery hard and brittle and. so much. so, that it would readily break whensubjected to impact and ordinary stresses and would not be suitable forluse until subjected to further treatment. This further treatment isgenerally termed draw- Y ing or tempering This drawing or temperingoperation produces such a change in the molecular construction of themetal as to reduce its toughness and hardness to the desired point towithstand loads, stresses and impacts Without breakage and permanentdistortion, and it consists generally in reheating the steel undertreatment to a heat lower than the original heat and then allowing thesame to copl at a slower rate. This secondary heating or drawingoperation is generally carried out by dipping the steel in a hot oilbath which is sufficiently hot to bring the steel only to the desiredheat. The degree of temper or drawing depends, in part, on the degree ofreheat, all of which requires skill and care in manipulation.

While the oil heat treating method may be employed to produce steelwhich satisfactorily meets the standard of practice that must be adheredto in each particular case and produces steel possessed of the necessarymetallurgical properties, yet it is quite objectionable for variousreasons. One objection is that it is a very expensive process involvinga plural stage operation. It requires frequent handling of material; theoperation and care of a plurality of furnaces, or the like; the care andchanging of the oil in the treating tanks'; and the upkeep of expensiveequipment, etc. It also requires skilled labor, and even with theskilled labor aided by pyrometers, etc., uniformity in the product doesnot always exist due to variation in judgment and skill of the variousworkmen.

Still another objection to this former method is that the pieces ofsteel, and particularly bars for automobile bumpers and springs, becomewarped when dipped in the oil. This latter condition requires peening cfthe distorted metal to bring it to its intended shape, and this peeningoperation is objectionable because it tends to destroy the alreadyestablished molecular arrangement and desired physical properties of thesteel and tends toward brittleness which is highly undesirable.Furthermore, the oil treated steel must be thoroughly degreased or tum`bled or sand blasted to clean it., all of which requires the use ofcostly apparatus and requires much time and operating expense.

An object of my invention is to provide a method of and apparatus forheat treating spring steel wherein all of the foregoing disadvantages ofthe oil heat treating method are eliminated, thereby greatly increasingtherate of production with a like decrease in cost.

Another object is to provide for the treatment of steel to produce adesired temper condition as accomplished by air, wherein the temperingof the steel is effected by the continuous and uniform application ofcool air to the same while in a heated condition. As the air is directedin contact with the heated metal and becomes heated by contact with thesame it is immediately yand continuously displaced and replaced by theconstantly supplied cool air.

Still another object is to provide an inexpensive method of heattreating spring steel involving a minimum amount of inexpensiveequipment and eliminating the necessity for the use of skilled labor.With my invention common labor may be employed, there being nopyrometers, furnaces, oil treating tanks, etc. to require the care ofskilled workmen.

A further object of my invention is to simplify the heat treatment ofsteel by accomplishing the hardening, drawing and tempering of the metalall at one and the same operation, wherein the results of theplural-stage heat treating operation of, the oil heat treating method isaccomplished in a single-stage operation, and wherein the cooling of themetal is under a variable control (may be fast or slow) which iseffective throughout the entire surface of the metal to cool the sameuniformly so that the metallurgical properties will be uniformthroughout.

A still further object of my invention is to prevent warping ordistortion of the steel under treatment during its treatment therebyavoiding further treatment, such as peening, which destroys thealready-established and desired metallurgical properties.

One highly desirable feature of my invention in addition to all theforegoing features and advantages is that I am able to produce a steelwhich can be readily cleaned for use by pickling in acid. This is a verysimple and cheap way of cleaning. The steel thus produced has all of thedesirable characteristics of that which is produced by the tediousandexpensive plural-stage oil heat treating method.

Other and further objects and advantages will become apparent as thisdescription progresses.

Although to facilitate the following descripltion I refer to myinvention as applied in t le manufacture of automobile bumpers andsprings, I do not desire to be limited to such use as it is obvious thatit is capable of use in various instances where it is desired to hardenand temper steel products or parts thereof.

In carrying out my method, say in the manufacture of bumper bars forautomobile bumpers, a bar of spring steel of the proper dimensions isheated to a desired high heat suitable to permit ready shaping of thesame and for carrying out the other operations to be described later.The heated bar is neXt subjected to a shaping operation, the desiredshaping tools being employed to give the sa me the final intended shape.As soon as the bar has been given its intended shape, as stated, andwhile it is still at a high heat, it is placed upon a flat metalsupporting surface in an air treating chamber. The surface upon whichthe bar is placed is cooled by water, or otherwise, topredetermined andvariable extents to prevent warping of such surface, which, in turn,prevents any distortion of the heated bar placed thereon from thatcause. If this were not done, the supporting surface may become heatedby contact with the heated bars to such an extent that it would warp outof shape and prevent an uneven supporting surface and cause distortionof the heated bar carried thereby. In case the bar under treatment is aflat bar, it may be placed di rectly upon the supporting surfacewith itsflat face contacting with the flat supporting surface, but in the eventthat the bar is of an irregular shape at any place throughout itslength, it may be placed upon the cooled supl porting surface on one ofits side edges so that it will not become distorted and lose the'already-given shape While in its heated state in the treating chamber.

After-the bar has been so placed in the treating chamber, blasts of airare constantly applied to such heating chamber, such air being confinedthereby and positively di rected into contact with the metal bar undertreatment. This air is fed in a cool state,

and is so confined and directed by the treating chamber and associatedparts and by its natural course of iow that it contacts uniformly withand throughout the surface of the bar. The temperature of the airadmitted is under control as well as its rate of` admission. The rate ofcooling is thus under control and dependent upon the temperature andrate of admission of the air to the treating chamber.. This action isalso further aided due to the fact that the air which becomes heated bycontact with the metal bar is rapidly displaced and replaced by theoncoming cool air so that the cooler air under treatment is constantlyin contact with the bar. There is a constant circulation of the cool airthroughout the treatin chamber and in contact with the bar un ertreatment, the incoming air being directed to accomplish this. Thus, thecooling of the bar may take place rapidly or' slowly and it is, at alltimes, sufficiently controlled to bring the steel down to the propercool condition, in the proper time, to produce the desired metallurgicalproperties in the same, that is, the pro er temper condition. After themetal bar as been thus cooled, and to an extent such that the heatremaining in the bar will not draw the temper, and to the point Wherethe molecular construction to the metal has adjusted itself to producethe proper metallurgical properties (the equivalent of those produced bythe Well-known oil heat treating method) it is removedfrom the oven andpermitted to cool sufficiently to permit ordinary handling and finaltreatment of the same.

One form of apparatus which I may employ in carrying out my invention isshown in the drawings wherein Figure 1 is a top plan view of anair-treating oven.,

Figure 2 is a side elevation of the treating oven of Figure 1.

Figure 3 is a partial end elevation ofthe structure of Figures 1 and 2.

Figure 4 is an enlarged top plan view of the Cooled supporting plate ofthe treating oven, a portion thereof being shown in section.

Figure 5 is a vertical section taken on line 5-5 of Figure 4.

Figure Gis a top plan View of another form of apparatus that may beemployed for carrying out my invention, and showing a portion of the topcut away.

Figure 7 is a partial elevated view of the structure of Figure 6.

Figure 8 is an enlarged detail view, partially in section, showing thearrangement of'the air delivery openings in the air pipes of thestructure of Figures 6 and 7.

Referring to the drawings, the form of apparatus shown may comprise arectangular-lyshaped supporting frame 1 supported by a leg 2 at eachcorner. AA surface or supporting plate member 3 is carried upon theframe 1 as shown in Figure 3, the member 3 being held in place by theframe in a suitable and desired manner. If desired the frame 1 and-member 3 may kbe skirted by a sheet metal f' ers.' Obviously, if nototherwise taken care of, the supporting plate 3 would become excessivelyheated by the bars 5 and would tend to Warp and thereby distort theheated bars carried thereby. One manner of taking Acare of thiscondition and preventing Warpfrom the top 3 to the bottom 3b of suchplate to divide its interior into a plurality of cool-` to produce thepartition and chamber con-l struction described. The top and bottom ofsuch plate may be formed comparatively thin due to the web or honey-combarrangement of its interior so that the top surface of such plate may bereadily-cooled and maintained in a cool state.

I preferably cool the plate 3 and maintain it cooled to a predeterminedextent regardless of the number of bars 5 placed thereon, and regardlessof the rapidity of replacement by passing a cooling fluid, preferablyWater, into the interior of the plate at 9 through the pipe 10 by anysuitable and desired flow-'control means (not shown). Each of theintersecting partition members 6 and 7 are provided with a plurality ofopenings 11 so placed that each cham-ber 8 has a plue rality of suchopenings leading into the adjacent chambers 8. The plate 3 is alsoprovided with an exit opening 12 connected to a discharge pipe 13.Therefore, the cooling fluid which enters through pipe 10 and inletopening circulates through the chambers 8, via the openings 11, andpasses to a suitable drain (or if desired to a cooling station and 1sused over again) through the outlet 12 and pipe 13. rl`he temperatureofthe Water which is passed through the plate may be controlled in anydesired manner, and the volume of cold Water per minute or other unit oftime may be controlled in any desired manner to cool the plate 3 to thepreferred and variable extent so as to maintain it at all times at sucha temperature that it Will not Warp.

To still further assist in cooling the plate 3 and to further strengthenit I provide the bottom 3b with a plurality of intersecting transverseand longitudinal ribs 14 and 15 which are arranged, preferably,alternately with the partitioning members 6 and 7 respectively. Thiseonstruction permits the bottom 3b to be formed comparatively thin toaid inthe cooling effect. Also the rib effect shown permits thecirculating air coming in contact with the thin portion and ribs to aidin cooling; and these 14 and 15 ribs also aid" in conducting heat to thelower and cooler frame portions.

The supporting plate 3 is disposed within an air-treating chamber 16 andthis plate 3 forms the bottom of such chamber. chamber 1 6 is formedwith, preferably, sectional sheet metal side Walls 16a and 16b and a top16. The sides and top of the chambers 16 are preferably formed sectionalfor facilitating construction and assembly, but may be formed of onecontinuous sheet or piece Without departing from my invention. The Wallsections may be supported by U- This y Cil shaped bar members 17 asshown in Figure 2, an'd any desired mode of attachment may be employed.The heating chamber is thus given a rectangular or other desired shapeWith depth, length and Width to suit the conditions of use, the size andcapacity of the chamber being variable as desired.

The ends of the chamber 16 are open (Figure 3) to permit ready egress ofthe heated air and scale, etc., as Will be referred to more particularlyherein fter.

The chamber 16 's provided with air admission means which Will now bedescribed. Each of the Wall sections of the chamber is provided With anair inlet of a Width substantially equal to the Width of the section.The air inlets of adjacent sections are arranged at opposite sides ofthe chamber and, preferably, at the upper outer edges thereof (Figs. 1and 3). This construction provides for the admission of air to thechamber 16 in such a manner as to effect complete and uniform'distribution of the same throughout the chamber, the adjacent airinlets or air currents being directed at close proximity in opposeddirections to accomplish direct distribution to all points regardless ofhow remote from the inlets. The air inlets so far described directparallel transverse currents of air; and at the center of the top 16c Iprovide tWo opposite air inlets Which direct air currents longitudinallyof the chamber 16 in opposite directions and across and in the path ofparallel currents. This further aids in the distribution of the parallelcurrents and provides additional air directly contacting with thematerial under treatment. The parallel air currents also carry airdirectly in contact with the material under treatment as Well as to allother parts of the chamber 16.

Each of the side inlets are connected to a suitable source (not shown)of cool air by 'means of pipes 18. JAll of these pipes are,

preferably, connected to a common source, but, if desired, may beconnected to 'different sources, the air 1n each instance belng variedas to temperature. and rate of flow to suit the conditions of use. A fanblower (not shown) might Well be employed for this purpose. Thecentrally disposed inlets in the top 3b of the chamber are alsoconnected to an inlet pipe 18a similar to the pipes 18 but, pref,-erably, of slightly greater capacity.A

Each of the pipes 18 are provided With a V-shaped or flaring nozzle 19which flares to a Width equal to the Width of the respectlve inlets towhich they are connected (Figures 1to 3). These nozzles are directeddownwardly and inwardly at such an angle that the air passingtherethrough and through the inlet Will' strike the material undertreatment and will also be directed normally and by the bottom of thechamber to all portions of the chamber with rapidity and uniformity.This action is aided by the flaring nature of the nozzles 19. The pipe18a at the center is provided With a double nozzle 20 having nozzleextensions 20a and 20" similar to the nozzle 19 and arranged anddirected in the same manner. The side nozzles 19 direct alternateparallel currents of air While the centerl nozzle 20a and 20" directlongitudinal cross currents of air thus positively insuring uniformdistribution of the air to the material under treatment and throughoutthe chamber 16. It is obvious that the number of air inlets may bevaried Without departing from my invention.

The side air inlets and the central inlet may all be connected to acommon air delivery source such as a fan blower (not shown) or each ofthesemay be connected to an independent source as desired.

In operation cooling air at the desired temperature and at the desiredrate is passed into the chamber 16 through the pipes 18 and 18a andnozzles 19, 20 and 20b yand as the same passes through the inlets intothe chamber it expands and is directed to all parts of the chamber.During this time the cooling fluid for cooling the plate 3 is beingcirculated through the pipe 10, cooling chamber 8 and pipe 13. With theapparatus in operation in the manner stated, the steel to be treated`for example a. bar 5 for a bumper, is first heated to the desired highheat and then shaped by suitable shaping tools and then placed in thechamber 16 in the manner and as indicated in Fig. 3. The bar 5 havingbeen thus placed in the chamber 16, the air passing through the pipes 18and 18a and uniformly present throughout the chamber 16, contactsuniformly with all portions of the bar andA cools the same. This coolingeffect is\ aided and, uniformity is aided, by the cooling effect of theplate 3 upon the bar 5. The cooling of the bar 5 may be hastened orretarded by varying the amount and rate of flow of the cooling airthrough the cooling pipes, as Well as varying the cooling of the plate3. The endsof the chamber 16 being open permits ready access thereto andpermits ready escape of the heated air and scale etc. carried by suchair. The arrangement of the side air inlets at each end causes the airand scale etc. to tend to pass out at the side so that the operator mayhave ready access Without interference by the heated air and objectscarried thereby. Furthermore, this arrangement as a Whole is such thatas the air contacts With the heated bars and becomes heated it israpidly displaced and ejected so` that the cool air is constantlycontacting with ment just described simultaneously. As theresult of theforegoing operations, the bars l receive metallurgical properties, theequivalent of those received by the oil heat 'treats ing process, allbeing accomplished by a singie stage operation, whereas in the oiltreating process a plural'stage operation is necessary. When the barsare removed from the treating chamber,V they are properly tempered andpossess suchl characteristics as to readily meet the requirements of thevSociety of Automotive Engineers.

Another form of apparatus for carrying out my invention is shown in'Figures 6 to 8.

.This apparatus is practically the same as that of the preferred formexcept as to the manner of admitting air to and distributing it inthechamber 16. In this modiied form, I may arrange4 a plurality of pipes 21and 21'* in the top, or other suitable part, of the chamber 16interiorly thereof as shown. These pipes are, preferably, all connectedtogether and are, in' turn, connected to a common source of supply (no tshown), preferably, an

air compressing dev1ce, by a pipe 22 having branches 22a and 22"; orthey may be individually connected to such a source. Each pipe isprovided with a plurality of opposed open.- ings 23 at each side, theseopenings being so arranged that they direct air currents or jetsdownwardly at an angle toward the plate 3 and the material undertreatment and uniformly throughoutthe chamber 16. The connected pipes 21and 21*L which may really be one continuously bent pipe with connecting.branches, are connected as stated, to a high pressure air source such asa compressor (not shown) so that cold air at high velocity is directedinto the chamber 16 through thc openings 23 in the manner and directionsindicated by the arrows in Figures 6 and 8.

' This high velocity 'cool air quickly cools the material undertreatment, or at any desired' rate, all of the effects and otheroperations ybeing the sameaas in connectionwith the preferred `form ofapparatus.

Thus it is seen that I have provided a simple 'but eiiicient method fortreating steel, particularly spring steel, for tempering the `same andwherein all of the disadvantages of the commonly used oil heat treatingmethod are eliminated, all of which is accom.- plished by a one-stageoperation wherein controlled cooling air is employed for effecting thecooling of the metal to temper the same. A minimum amount of equipmentis necessary, eliminating the necessity for the use of skilled labor.Production is increased with a decreasev in cost of production. When themetal has once been shaped, this shape is maintained throughout thefollowing operations without distortion.

. While I have shown but two forms of apparatus for carrying out myinvention, it is to be understood that various other forms andmodifications maybe resorted to without departing from the spirit andscope of my inrention as set forth in the claims which fol- I claim:

1. Inl anapparatus for hardening and tempering steel, a treating chamberincluding an artificially cooled bottom, side and top walls, a pluralityof air inlets at the sides, adjacent lnlets being at the opposite sidesand directed downwardly and inwardly, and air inlets in the top directedin opposite directions and downwardly and inwardly.

2. An apparatus for treating steel comprising a chamber having anartificially cooled bottom, air delivery means at the sides of saidchamber for directing air inwardly and downwardly toward said bottom,other air delivery means at the top of said chamber and arranged todirect air downwardly and inwardly toward said bottom and across thepath of the air delivered by said first-mentioned delivery means.

3. An `apparatus for treating steel comprisin an open-ended chamberhaving an artificially cooled bottom, airl delivery means at the sidesof said chamber for directin parallel blasts of air from the opposite sies inwardly and downwardly Ytoward said bottom, other air delivery meansat the top of said chamber arranged to direct air downwardly andinwardly toward said bottom and in opposite directions across the pathof the air delivered by said side air delivery means.

4. In an apparatus for hardening and tempering spring steel in asingle-stage operation, a chamber having a bottom adapted to carry thesteel under treatment, means for cooling said bottom and for maintainingthe same cooled to a predetermined degree, air inlets at the lsides ofsaid'chamber, the adjacent inlets being arranged at opposite sides ofsaid chamber for conducting airl in opposite directions into saidchamber and in Contact with said bottom, air conductors connected tosaid inlets other air inlets in the top of said chamber for conductingair into said chamber and in contact with said bottom and across thepath of the air admitted through said side inlets, and air conductingmeans connected to said latter inlets.

5. In an apparatus for hardening and tempering spring steel in asingle-stage operation, a chamber having a bottom adapted to carry thesteel under treatment, means for cooling said bottom and for maintainingthe same cooled to a predetermined deglree including cooling iuidconduits lea 'ng to, through and from said bottom, air inlets at thesides of said chamber, the.adjacent inl lets being arranged at oppositesides of said chamber for conducting air in opposite directions intosaid chamber and in contact with said bottom, air conductors havingflared nozzles connected to said inlets, and other air inlets in the topof said chamber for conducting air into said chamber and in contact withsald bottom and across the path of the air admitted through said sideinlets, air conducting means having flared nozzles connected to saidlatter inlets. f

6. In Aan apparatus for treating steel to harden and temper the samecomprising a chamber having a bottom adapted to receive the steel in aheated condition, means for cooling said 'bottom andY maintaining thesame cooled,'means for passing lateral and parallel blasts of air intosaid chamber in contact with the steel under treatment, the adjacentparallel blasts being directed in opposite directions, and means forpassing longitudinal blasts of air into said chamber in oppositedirections and in contact with said steel across the paths yof saidparallel blasts.

7. In an apparatus for treating spring steel, a supporting means forreceiving and carrying the steel in its heated condition,com. prising ahollow plate, transverse and longitudinal intersecting vpartitionmembers carried by said plate dividing its hollow interior intochambers, vconnecting means between ad` jacent chambers, means forconducting a cooling fluid into one of said chambers, and dischargemeans connected to another of Said chambers for carrying said coolingHuid away.

8. In an apparatus for treating spring steel, a supporting means forreceiving and carrying the steel in its heated condition, comprising ahollow plate, having comparatively thin and connected top and bottomwalls and having the space between said top and bottom walls dividedinto a plurality of connected compartments, connections between each ofthe adjacent compartments, a cooling iuid .delivery conduit connected toone of said compartments, and a discharge conduit connected to anotherof said compartments, the arrangement being such that said cooling fluidis continuously passed through all of said compartments to maintain saidplate walls cooledv to a predetermined extent.

9. In an apparatus for hardening and tempering spring steel, a supportfor the steel in its heated condition during treatment comprising avplate having thin and spaced top and bottom walls connected by side andend Walls, intersecting partitioning members between said top and bottomwalls dividing said space into a plurality of compartments, means forconnecting all ofy said compartments with eachother, delivery conduitmeans connected to oneof said compartments, discharge conduit meansconnected to `another of said compartments, the arrangement being suchthat a cooling fluid is passed through said delivery conduit, each ofsaid compartments and through said discharge conduit in the successionnamed to maintain said plate r cool, and transverse and longitudinalintersecting ribs formed externally on said bottom wall. Y

r 10. In an apparatus for treating spring i steel, a supporting meansfor receiving and carrying the steel in its heated condition, comprisinga hollow plate, transverse and longitudinal intersecting partitionmembers carried by said plate dividing its hollow interior intochambers, connecting means between adjacent chambers, means forconducting a cooli ing fluid into one of said chambers, discharge meansconnected to another of said chambers for carrying said cooling fluidaway, and transverse and longitudinal ribs formed on the other bottomportion of said plate.

In testimony whereof, I' have subscribed my name.

HERBERT W. TINKER.

